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The results of studying a HIT (heterojunction with an intrinsic thin layer) Ag/ITO/a-Si:H(p)/a-Si:H(i)/c-Si(n)/a-Si:H(i)/a-Si:H(n+)/ITO/Ag solar cell by the capacitance–voltage characteristic and current deep-level relaxation transient spectroscopy methods are presented. The temperature dependence of the capacitance–voltage characteristics of the HIT structure and deep-energy-level parameters are studied. The results of comprehensive studies by the above methods are used to determine the features of the energy-band diagram of actual HIT structures.

An experimental study of the capacitance–voltage (C–V) characteristics and deep-level transient spectroscopy (DLTS) of p+–p0–i–n0 structures based on undoped GaAs, grown by liquid-phase epitaxy at two crystallization-onset temperatures To (950 and 850°C), with optical illumination switched off and on, are performed. It is shown that the p0, i, and n0 layers of epitaxial structures are characterized by the presence of defects with deep donor- and acceptor-type levels in concentrations comparable with those of shallow donors and acceptors. Interface states are found, which manifest themselves in the C–V characteristics at different measurement temperatures and optical illumination; these states form an additive constant. A distinct temperature dependence of the steady-state capacitance of the structures is revealed. It is found that the injection of minority carriers under an applied positive filling pulse and optical recharging lead to modification of the structure and, correspondingly, the DLTS spectra of the p+–p0–i–n0 structures. It is revealed that the p+–p0–i–n0 GaAs structures grown at To = 850°C are characterized by a lack of interface states and that the recharging of acceptor-type deep traps under illumination does not change the C–V characteristics. The conventionally measured DLTS spectra reveal the presence of two hole traps: HL5 and HL2, which are typical of GaAs layers.

The specific features of detecting the contribution of the characteristic intrinsic defect in semi-insulating GaAs to photocurrent relaxation are considered. A detailed analysis of the relaxation kinetics based on approximation by the sum of exponential components is presented. The approximation results are compared with the data of photo-induced current transient spectroscopy.

Deep-level transient spectroscopy (DLTS) has been used to study p-n junctions fabricated by implantation of boron into epitaxial 4H-SiC films with n-type conductivity and the donor concentration (8–9) × 1014 cm−3. A DLTS signal anomalous in sign is observed; this signal is related to recharging of deep compensating boron-involved centers in the n-type region near the metallurgical boundary of the p-n junction.

The features of the DLTS detection of defects with retrappability of thermally excited carriers due to a large value of effective capture cross section are considered. Indications allowing identification of the implementation of the given model are found.

The method of transient spectroscopy is one of the basic methods widely used for determining the parameters of defects, which are the origin of deep levels in the semiconductor-material band gap. With the purpose of increasing the accuracy of determining the concentration and deep-level parameters describing the character of the isothermal capacitance relaxation, a statistical method of processing the results of its measurements based on the statistical solution-search algorithm is proposed.

Using deep-level transient spectroscopy and capacitance-voltage measurements, the effect of electric field on ionization of the sulfur-related DX center is investigated for n-In1 − xGaxP layers (x = 0.65) grown by vapor-phase epitaxy. It is shown that, upon increasing the electric field strength from 1.3 × 104 to 1.9 × 105 V/cm, the activation energy of the center decreases from ∼0.38 to ∼0.26 eV, and the ionization process is governed by multiphonon tunneling. By the estimated tunneling time of the defect, it is concluded that the DX center corresponds to a model of large lattice relaxation.

The potentialities of photoinduced transient spectroscopy in terms of investigation of defect centers in wide-band-gap semiconductors are presented. An experimental system dedicated to measurements of the photocurrent transients at temperatures 20–800 K is described and a new approach to extraction of trap parameters from the photocurrent relaxation waveforms recorded in a selected temperature range is presented. The approach is based on the two-dimensional analysis of the waveforms as a function of time and temperature using the correlation procedure. As a result, three-dimensional images showing the temperature changes of the emission rate for detected defect centers are produced and a neural network method is applied to determine the parameters of defect centers. The new approach is exemplified by studies of defect centers in high-resistivity GaN: Mg and semi-insulating 6H-SiC: V.

Capture centers (traps) are studied in silicon-on-insulator (SOI) structures obtained by bonding and hydrogen-induced stratification. These centers are located at the Si/SiO2 interface and in the bulk of the split-off Si layer. The parameters of the centers were determined using charge deep-level transient spectroscopy (Q-DLTS) with scanning over the rate window at fixed temperatures. Such a method allows one to study the traps near the Si midgap at temperatures near 295 K. It is shown that the density of traps with a continuous energy spectrum, which are located at the bonded Si/SiO2 interface, decreases by more than four orders of magnitude at the mid-gap compared with the peak density observed at the activation energy E a ≈0.2–0.3 eV. The capture centers are also found in the split-off Si layer of the fabricated SOI structures. Their activation energy at room temperature is E a =0.53 eV, the capture cross section is 10−19 cm2, and the concentration is (0.7–1.7)×1013 cm−3. It is assumed that these capture centers are related to deep bulk levels induced by electrically active impurities (defects) in the split-off Si layer close to the Si/SiO2 interface.

The investigation of high-resistivity CdS single crystals by photoelectric deep-level transient spectroscopy (PEDLTS) is discussed. Computer simulation of the experiment is carried out. This simulation enables us to compare the results obtained by the PEDLTS and thermally stimulated conductivity methods. The experimental potentials of these methods are compared.

Starting from the data of deep-level transient spectroscopy, the charge fluctuations at the interface between the top Si layer and buried insulator in Si-on-insulator structures are evaluated. The interface was prepared by bonding Si with the thermally oxidized substrate. The magnitude of fluctuations at the interface is found to be equal or exceed (1.5–2.0)×1011 cm−2 against the charge background of ∼5×1011 cm−2 at this interface. It is shown that the fluctuations are most likely associated with the negative charge at the surface states rather than with the fluctuations of the fixed positive charge within oxide.

The origin of a broad U band in spectra obtained using deep-level transient spectroscopy (DLTS) of n-GaAs irradiated with fast neutrons and 65-MeV protons was investigated. It is believed that this band is presumably a superposition of two peaks related to two defects P2 and P3 which have been well documented in GaAs and reside within defect clusters. The DLTS spectra were calculated taking into account the nonuniform distribution of these defects in a sample and the built-in electric fields induced by corresponding inhomogeneities.

The defects in a high-resistivity p-GaSe single crystal are investigated by the method of photoinduced current transient spectroscopy. The results show the presence of traps corresponding to the gallium vacancy and extended defects. The traps with thermal-activation energies of 0.13, 0.39, and 0.53 eV are also detected. Their nature is discussed.

ZnTe heteroepitaxial layers and ZnTe/Zn1−xCdxTe/ZnTe strained quantum-confinement structures grown by molecular-beam epitaxy on GaAs(001) were studied by low-temperature cathodoluminescence spectroscopy and current-relaxation deep-level transient spectroscopy (DLTS). A peak related to electron emission from the ground size-quantization level in the conduction-band was observed in the DLTS spectra of quantum-confinement structures. The conduction-band offset parameter QC was determined from the DLTS and cathodoluminescence data. For Zn1−xCdxTe/ZnTe single-quantum-well structures with x=0.2–0.22, QC equals 0.82 ± 0.05. The effect of internal elastic strain on the band offsets and QC at the CdxZn1−xTe quantum well interfaces was calculated; the results of calculations agree well with experimental data.

A study of charge relaxation processes in metal-insulator-semiconductor structures containing the rare-earth oxides Gd2O3 and Lu2O3 as the insulator has been performed using the deep-level transient spectroscopy (DLTS) method in combination with a study of nonlinear oscillations in the metal-insulator-semiconductor structure connected to an external inductive circuit. On the basis of the DLTS results and the variation with temperature of the configuration of the period multiplicity regions of the controlling parameters (the amplitude and frequency of the applied voltage) it is shown that the generation of nonlinear oscillations in a metal-insulator-semiconductor structure is governed by the properties of the insulator-semiconductor interface, in particular, the density of surface states and the capture cross sections.

Deep-level transient spectroscopy is used to study the dependence of the concentration of the donor-and acceptor-type radiation defects in silicon on the duration of irradiation with low-intensity fluxes of β particles (I ≈ 9 × 105 cm−2 s−1). It is found that the concentrations of the defects C i , C i -C s , and/or V-O in n-Si and the defects V-B, C i -O i , and/or V 2-O-C in p-Si vary nonmonotonically.

Deep-level transient spectroscopy has been used to study the effect of Ge atoms on the behavior of Mn in Si. It is shown that Ge atoms introduced into Si during growth manifest no electrical activity, even though their concentration is rather high: 1016–1019 cm−3. It is established that the presence of Ge atoms in the Si lattice enhances the efficiency of the formation of the deep levels E c -0.42 eV and E c -0.54 eV, which are associated with Mn in the Si lattice: the concentration of these deep levels in Si〈Ge, Mn〉 samples is a factor of 3–4 greater than in Si〈Mn〉. It is found that the presence of Ge atoms stabilizes the properties of the Mn levels in Si: They anneal more slowly than in Si〈Mn〉 by a factor of 5–6. It is assumed that the detected effects are associated with the features of the defect structure of Si doped with Ge and Mn.

Deep levels in semi-insulating CdS single crystals grown with a variation in the stoichiometric composition are investigated by photoinduced-current transient spectroscopy (PICTS). A series of deep levels with a thermal activation energy ranging from 0.066–0.54 eV is revealed. It is found that the signal ratio in the set of spectra disagrees with the basic PICTS model. A procedure for evaluation of the concentration of deep levels is developed for these conditions.

Deep-level transient spectroscopy is used to study the emission of holes from the states of a vertically coupled system of InAs quantum dots in p-n InAs/GaAs heterostructures. This emission was considered in relation to the thickness of a GaAs interlayer between two layers of InAs quantum dots and to the reversebias voltage Ur. It is established that hole localization at one of the quantum dots is observed for a quantum-dot molecule composed of two vertically coupled self-organized quantum dots in an InAS/GaAs heterostructure that has a 20-A-thick or 40-A-thick GaAs interlayer between two layers of InAs quantum dots. For a thickness of the GaAs interlayer equal to 100 A, it is found that the two layers of quantum dots are incompletely coupled, which results in a redistribution of the hole localization between the upper and lower quantum dots as the voltage Ur applied to the structure is varied. The studied structures with vertically coupled quantum dots were grown by molecular-beam epitaxy using self-organization effects.

Deep-level transient spectroscopy is used to study charge-carrier emission from the states of separate quantum dots in InAs/GaAs p-n heterostructures grown on (100)-and (311)A-oriented GaAs substrates in relation to the reverse-bias voltage U. It is established that the structures under consideration exhibit different bias-voltage dependences of the Stark shift for the energy levels of the quantum-dot states on the value of U.